/**
 * The utillib library.
 * More information is available at http://www.jinchess.com/.
 * Copyright (C) 2002 Alexander Maryanovsky.
 * All rights reserved.
 *
 * The utillib library is free software; you can redistribute
 * it and/or modify it under the terms of the GNU Lesser General Public License
 * as published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * The utillib library is distributed in the hope that it will
 * be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser
 * General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with utillib library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

package free.util;

import java.util.Enumeration;
import java.util.NoSuchElementException;


/**
 * An implementation of the Enumeration interface which enumerates a single
 * item. Note: This class is not thread safe.
 */

public class SingleItemEnumeration implements Enumeration {


    /**
     * The sole item.
     */

    private Object item;


    /**
     * Becomes true when we've returned the sole item.
     */

    private boolean done = false;


    /**
     * Creates a new SingleItemEnumeration which enumerates the specified item.
     */

    public SingleItemEnumeration(Object item) {
        this.item = item;
    }


    /**
     * Returns the sole item or throws a <code>NoSuchElementException</code>.
     */

    public Object nextElement() {
        if (!hasMoreElements())
            throw new NoSuchElementException();

        done = true;

        Object item = this.item;
        this.item = null; // We don't want to hold a reference to it any longer than we need.
        return item;
    }


    /**
     * Returns true if there are more elements in the enumeration.
     */

    public boolean hasMoreElements() {
        return !done;
    }


}
